Catch up on today's top five analyst downgrades with this list compiled by The Fly: 1. Biogen (BIIB) downgraded to Buy from Conviction Buy at Goldman Sachs with analyst Terence Flynn saying pipeline and balance sheet optionality are taking longer to materialize than expected but valuation reflects limited value to Aducanumab or Biogen's Phase 2 neuro pipeline. 2. GrubHub (GRUB) downgraded to Neutral on valuation at Roth Capital with analyst Darren Aftahi citing valuation. 3. Paccar (PCAR) downgraded to Sector Perform from Outperform at RBC Capital and to Neutral from Buy at BofA/Merrill. 4. Caterpillar (CAT) downgraded to Neutral from Outperform at Daiwa. 5. Edwards Lifesciences (EW) downgraded to Market Perform from Outperform at Northland. This list is just a portion of The Fly's full analyst coverage. To see The Fly's full Street Research coverage, click here.